---

Aim:

To study asexual reproduction, specifically binary fission in Amoeba and budding in Yeast and Hydra, with the help of prepared permanent slides.

Material Required:

1. Permanent slide of Amoeba showing binary fission.
2. Permanent slide of Yeast showing budding.
3. Permanent slide of Hydra showing budding.
4. A compound microscope.
5. Lens cleaning paper.
6. Practical notebook and pencil for drawing.

Theory:

Asexual reproduction is a mode of reproduction in which a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to the parent, i.e., they are clones. There are various types of asexual reproduction, including fission, budding, fragmentation, etc.

1. Binary Fission: This is a method of asexual reproduction common in unicellular organisms like Amoeba, Paramecium, and bacteria. In this process, the parent cell divides into two equal-sized daughter cells. The process involves two main steps:
   • Karyokinesis: The division of the nucleus.
   • Cytokinesis: The division of the cytoplasm.
     The parent identity is lost as it divides to form two new individuals.
2. Budding: In this method, a new organism develops from an outgrowth or a bud on the parent’s body.
   • In Yeast (Unicellular): A small bulb-like projection, called a bud, forms on the parent cell. The parent’s nucleus divides, and one daughter nucleus migrates into the bud. The bud grows and may eventually detach or remain attached, forming a chain of cells.
   • In Hydra (Multicellular): A bud develops as an outgrowth due to repeated cell division at one specific site on the body wall. This bud grows into a tiny individual, develops a mouth and tentacles, and eventually detaches from the parent body to live as an independent organism.

Procedure:

1. Set up the compound microscope on a flat, well-lit surface. Clean the eyepiece and objective lenses with lens cleaning paper.
2. Take the prepared slide of Amoeba showing binary fission and place it on the microscope stage. Secure it with the clips.
3. Adjust the mirror to get a bright and evenly illuminated field of view.
4. First, focus the slide under the low-power objective lens (10x) using the coarse adjustment knob.
5. Once the image is visible, switch to the high-power objective lens (45x) and use only the fine adjustment knob to get a sharp, clear image.
6. Carefully observe the different stages of binary fission visible on the slide. Note the changes in the nucleus and cytoplasm.
7. Draw a neat, labeled diagram of the observed stages in your notebook.
8. Repeat steps 2 to 7 for the prepared slide of Yeast showing budding.
9. Repeat steps 2 to 7 for the prepared slide of Hydra showing budding. (Note: Hydra is a larger organism, and its budding might be clearly visible even under the low-power objective).

Observation:

A. Binary Fission in Amoeba:

1. A parent Amoeba cell with a distinct nucleus, cytoplasm, and pseudopodia is observed.
2. In a dividing cell, the nucleus is seen elongating and then dividing into two (Karyokinesis).
3. Following nuclear division, a constriction appears in the cytoplasm, which deepens progressively.
4. Finally, the cytoplasm divides completely (Cytokinesis), resulting in two smaller, genetically identical daughter Amoeba cells.

(Space for Diagram)

A neat, well-labeled diagram showing the stages of binary fission in Amoeba should be drawn here.
Labels should include: Parent Amoeba, Nucleus, Elongating Nucleus, Constriction of Cytoplasm, Daughter Amoebae.

B. Budding in Yeast:

1. Many individual oval-shaped yeast cells are observed.
2. Some parent cells show a small bulb-like outgrowth called a bud.
3. In some cells, the bud is small, while in others, it has grown almost to the size of the parent cell.
4. A chain of yeast cells is also observed where buds have remained attached to the parent cell and have started budding themselves.

(Space for Diagram)
A neat, well-labeled diagram showing budding in Yeast should be drawn here.
Labels should include: Parent Yeast Cell, Nucleus, Bud, Chain of Buds.

C. Budding in Hydra:

1. A parent Hydra with a cylindrical body, a mouth surrounded by tentacles at one end, and a basal disc at the other is observed.
2. A small bulge or outgrowth is seen on the side of the body wall of the parent Hydra.
3. In a more developed stage, this bud has grown and developed its own mouth and small tentacles.
4. The bud is seen attached to the parent, from which it derives its nutrition. It will eventually detach to become an independent Hydra.

(Space for Diagram)

A neat, well-labeled diagram showing budding in Hydra should be drawn here.
Labels should include: Parent Hydra, Tentacles, Mouth, Bud, Developing Bud.

Result:

The prepared slides of Amoeba, Yeast, and Hydra were observed under the compound microscope.

1. The Amoeba slide showed asexual reproduction by binary fission, where one parent cell divides into two daughter cells.
2. The Yeast slide showed asexual reproduction by budding, where a small bud grows on the parent cell.
3. The Hydra slide showed asexual reproduction by budding, where a multicellular bud develops on the parent’s body.

Precautions:

1. The microscope and slides should be handled with care to avoid damage.
2. Always start focusing with the low-power objective lens.
3. When using the high-power objective, use only the fine adjustment knob to focus.
4. Ensure the slide is clean before placing it on the stage.
5. Draw the diagrams as observed under the microscope.
6. Place the slides back in their respective boxes after observation.